FAQ

Yes, with JORDAHL^® hot rolled anchor channels it is possible to take small to medium loads along the length of the anchor channels. Then instead of using the Hook-Head or Hammer- Head bolts, special double notched toothed bolt types JKB and JKC should be used. The installation torques of these bolts are higher creating a groove inside the channel lips thereby enhancing its load carrying capacity along the longitudinal direction of the anchor channel.

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Since the beginning of 2011 the JORDAHL GmbH offers a user-friendly software for free download. This facilitates users to switch from the previous rigid design according to tables on a flexible design according to ETA.

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Yes, the design of anchor channels is carried out according to the provisions of the ETA and when selecting high concrete grade, you can influence the load carrying capacity. However, it depends on the type of failure as well. If load carrying capacity is restricted due to a failure in the concrete then you can increase the concrete resistance by improving the quality of the concrete. However, if it is a steel failure, increased resistance will not be possible.

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If the load carrying capacity is limited by steel resistance, there could be either a connection failure between the channel/anchor or the bolt/channel. In the first case, it is possible to reduce the distance between anchors by increasing the number of anchors. In the second case, by increasing the number of bolts, the load carrying capacity can also be increased.

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Hot-rolled profiles are hot rolled from a single block. Thus they are free of internal stresses and they have increased channel lips. Due to the triangular shape of the channel lips, it is possible to apply high torques and thus high bolt tension forces. They can be used very well for dynamic loads and to improve the transmission of longitudinal forces. The new hot-rolled profiles for ETA 09/0338 also have an increased shear steel capacity of 30% compared to the cold-formed profiles.

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Yes, basically one can increase the load carrying capacity of concrete from edge reinforcement. However, it depends upon the type of failure whether it is concrete failure or steel failure. If the failure due to critical load condition is in concrete then one can increase the concrete resistance with the help of additional reinforcement. On the other hand, if the failure is a steel failure then it will not increase the resistance.

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Since the shaft of the T-bolt is not directly supported by the bracket, the T- bolt gets additional bending stresses in this case. Therefore in the JORDAHL^® Expert design software; there is the option to consider slotted holes in the bracket and additional bending of the bolt. The degree of restraint is depending on the stiffness of the washer used, for typical bracket connection recommended values are between 1.6 and 1.8. If the slots in the brackets will be filled with grout or cementious floor pavement later, the bending can be neglected and no slots have to be considered in the calculation.

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Fatigue verification should be carried out when anchor channels are subjected to regular load cycles (e.g. fastening of cranes, reciprocating machines and guide rails of elevators). Verification for the dynamic/fatigue loading can be done in JORDAHL^® EXPERTSoftware by activating the option “Dynamic fatigue loads” and by inputting the characteristic fatigue load range values (DN). In general, the calculations for the fatigue strengths are carried out on 2 million load cycles (2 x 106).

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The design of reinforced concrete traditionally assumes that concrete is cracked wherever tensile stresses might occur. Cracks may be caused by external loads, as well as concrete creep and shrinkage, temperature variations, and settlement. As such, many reinforced concrete members are designed under the assumption that the concrete is cracked under service load. Additionally, concrete structures in regions of moderate to high seismic risk are designed assuming cracked concrete conditions. In exceptional cases for example post tensioned slabs, columns and walls, the condition of the concrete can be assumed to be un-cracked.

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The calculation method for the anchor channels differentiates between verifying at the point where the load is acting (bolt) and the anchorage. JORDAHL^® Expert automatically determines the worst load case scenario for the critical anchor. The anchor channel is then designed for this load position and is displayed on the screen and the printout.

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At the end of the T-bolt shank there are safely notches visible to enable an easy check that the T-bolt has been fully rotated into the channel. Toothed and double toothed T-bolts have two parallel notches. During the placing of bolts into the channel these safety notches must be perpendicular to the longitudinal axis of the anchor channel otherwise full load carrying capacity cannot be achieved.

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Due to increasing demands on products in case of a fire (i.e. for slabs and roof constructions up to 120 minutes of fire exposure) and new applications such as power plant constructions and tunnelling, we decided to make JORDAHL^® anchor channels performance according to fire resistance class R120. Anchorage in concrete is very important during a fire so JORDAHL^® anchor channels are a safe way to transfer loads into the structural concrete in case of a fire.

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Fatigue verification should be done when anchor channels are subjected to regular load cycles (e.g. fastening of cranes, reciprocating machines and guide rails of elevators). With JORDAHL^® EXPERT, this can be achieved by activating the option “dynamic fatigue loads” and by input of the characteristic fatigue load range values.

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In the ACI 318-08 and ACI 318-11 editions, Studrails^® are designed using the provisions of Clause 11.11.5. These design procedures, equations and limits were adopted from ACI 421.1R-99.

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The slab effective depth for the Studrail^® design is the average of the two orthogonal directions. Thus, the slab effective depth is calculated as the slab thickness minus the top concrete cover minus the diameter of the top flexural reinforcing bars.

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Yes, this upside-down installation is possible but is generally only recommended when the rebar installation has proceeded prior to delivery of the Studrails^®. For this alternate installation, it is important to ensure proper positioning of the Studrails^®. We could provide a letter outlining the special procedures that should be followed to ensure proper placement for this installation.

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The function of a Studrail^® is to intercept punching shear cracks that develop in the slab in the vicinity of a slab-column connection. The studs on each Studrail^® are anchored at the top with the oversized stud head, and at the bottom with the base rail. The base rail is also used to provide the proper spacing of the studs away from the column face. As long as the spacing between the studs does not exceed the design dimension, continuity of the base rail is not required for the Studrails^® to provide the design strength.

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"Round anchors are prefabricated and are connected to the back of the channel by a mechanical process and the connection is similar to a riveted connection. Due to the automatic fabrication of round anchors, a consistent high quality can be achieved to allow a reliable connection. Compared to the I-anchors, R-anchors can be installed very easily due to a smaller anchor head. I-anchors are welded to the back of the channel. They are wider than the round anchors. Principally both anchors produce a similar breakout cone in concrete and attain the same load bearing capacities. "

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